Synthesis, characterization and size dependent energy band gap of binary CdSe quantum dot and its nanoparticle film (original) (raw)
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Investigation of size dependent structural and optical properties of thin films of CdSe quantum dots
Materials Research Bulletin, 2011
Cadmium selenide (CdSe) quantum dots were grown on indium tin oxide substrate using wet chemical technique for possible application as light emitting devices. The structural, morphological and luminescence properties of the as deposited thin films of CdSe Q-dot have been investigated, using X-ray diffraction, transmission electron microscopy, atomic force microscopy and optical and luminescence spectroscopy. The quantum dots have been shown to deposit in an organized array on ITO/glass substrate. The as grown Q-dots exhibited size dependent blue shift in the absorption edge. The effect of quantum confinement also manifested as a blue shift of photoluminescence emission. It is shown that the nanocrystalline CdSe exhibits intense photoluminescence as compared to the large grained polycrystalline CdSe films. ß
2015
A well adherent nanocrystalline thin film of cadmium selenide (CdSe) has been successfully deposited from chemical bath containing cadmium acetate, tartaric acid, ammonia and sodium selenosulphate, at a bath temperature of 85 0 C and a pH of 9.5. The films were characterized using a variety of techniques. Powder X-ray diffraction revealed a cubic phase of CdSe nanocrystalline thin film with preferred orientation along the (111) plane. The SEM micrographs showed the film surface was composed of spherically shaped grains over the entire glass substrate. The elemental composition of the thin film was confirmed by energy dispersive X-ray spectroscopy. The optical band gap energy was found to be 1.86 eV.
Nanotechnology is a study on materials which deal with the structures in nanometer scales, typically ranging from sub-nanometers to several hundred nanometers. Nanocrystals is the material whose crystal structure is measured in nanometers and also known as quantum dots. Nanocrystals have a very interesting optical properties and characteristics where a range of samples of different radii, will emit different wavelengths when excited by the same wavelength of light. Some of the properties are the unique excellent optical properties, such as wide absorption and narrow emission spectra, large extinct, coefficients, resistance to photo-bleaching, long fluorescence lifetime, and size-tunable emission.
Journal of Materials Science: Materials in Electronics, 2016
Cadmium selenide (CdSe) thin films have been prepared by chemical bath deposition on glass substrates in chemical solution and the pH controlling agent has been altered. The band gap energy of CdSe thin films was determined by using UV-visible spectra. The structural and surface morphological properties were studied by X-ray diffraction and scanning electron microscopy. Furthermore, Rutherford backscattering spectroscopy, as a powerful technique in surface science, was used to investigate the stoichiometry and the variation of the depth profile concentration of Cd and Se elements along the thickness of the prepared samples. The result indicated that the pH has a crucial role in physical properties of prepared CdSe thin film and can control the procedure of deposition to achieve the desired value of band gap energy, quality of crystallity and homogeneity of the prepared thin films.
Optical and Structural Properties of CdS Quantum Dots Synthesized Using (MW-CBD) Technique
Iraqi Journal of Nanotechnology, 2020
In the present study, the microwave heating method was used to prepare cadmium sulfide quantum dots CdSQDs films. CdS nanoparticles size average obtained as (7nm). The morphology, structure and composition of prepared CdSQDs were examined using (FE-SEM), (XRD) and (EDX). Optical properties of CdSQDs thin films formed and deposited onto glass substrates have been studied at room temperature using UV/ Visible spectrophotometer within the wavelength of (300-800nm), and Photoluminescence (PL) spectrum. The optical energy gap (Eg) which estimated using Tauc relation was equal (2.6eV). Prepared CdS nanoparticles thin films are free from cracks, pinholes and have high adhesion to substrate.
Egyptian Journal of Chemistry
Q UANTUM dots are very tiny semiconductor particles used in solar cells; their optical and electronic properties differ from those of macro particles. They could improve the performance of solar cells if they are prepared in the suitable size. In this work, cadmium sulfide (CdS) quantum dot (QD) thin films were prepared on transparent conductive fluorinedoped tin oxide substrates. The formation and deposition of CdS QDs were optimized using the chemical bath deposition method under varied operating conditions (precursor concentration, and temperature). Chemical bath deposition is an effective method for the deposition of CdS on porous TiO 2 films as QDs. The structural, morphological, and optical properties of the prepared CdS thin films were studied using X-ray diffraction, field-emission scanning electron microscopy, Raman spectroscopy and UV-Vis-near infrared spectroscopy. The particle size of the CdS QDs was calculated to be 3-7 nm from the observed X-ray diffraction pattern. The band gap was blue shifted in the UV-Vis absorption spectrum compared with that of bulk CdS, confirming the formation of CdSQDs.
Hydrothermally synthesized cadmium selenide quantum dot for solar cell application
2012
Hydrothermal synthesis autoclave reactor offers simple, safer and environmentally friendlier process for the preparation of valuable nanoparticles. In this study, cadmium selenide (CdSe) quantum dot (QD) were successfully synthesized via one-step hydrothermal synthetic route at 195 o C. The reactant mixtures used for the synthesis was added into Teflon and comprises 15 mg of selenium (Se) powder, 15 mg of cadmium oxide (CdO), 20 ml of octadecene (OTD), 10 ml of oleic acid (OA) and 1 ml of trioctylphosphine (TOP). The synthesis lasted for 3 hours 20 minutes. The synthesized CdSe QDs were characterized using optical absorption spectroscopy, fluorescence spectroscopy (PL), scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDAX). The broad absorption peak of the sample depicted the suitability of the sample for photovoltaic application while the fluorescence peaks was assigned to band edge emission to shallow and deep trap states. AFM and SEM microstructure images revealed the surface morphology and the crystal orientation of CdSe QD while the QD size and particles distribution were obtained using TEM and FESEM. The EDX were used to obtain the compositional ratio of the materials in the synthesized CdSe QD sample. The formation mechanisms were discussed on the basis of the experimental results and the quantum dots were found to be stable for about three months.